Research during the last year has focused on plasma apolipoproteins (apo) concentrations and isoforms in patients with coronary artery disease as well as familial hypercholesterolemic subjects. Patients with familial hypercholesterolemia (FH) have decreased apoA-I and elevated apoE plasma concentrations. Of major importance was the finding that the LDL receptor activity in patients with FH was highly correlated with plasma cholesterol level, severity of clinical disease, and response to treatment. Ongoing studies of the clinical course in FH reveals the progressive nature of supravalvular, valvular, and coronary artery ostial disease which is highly correlated with the clinical progression of disease. Apolipoprotein levels have also been evaluated in clinic patients with premature coronary artery disease. Both apolipoprotein A-I and C-II were highly correlated in the population with the coronary artery disease and more clearly identify the atherosclerotic population than plasma cholesterol and triglyceride levels. To further evaluate the apolipoproteins in various dyslipoproteinemic patients a new two-dimensional electrophoretic technique has been developed and is currently being use successfully to determine apolipoprotein concentrations, molecular weight, and to identify apolipoprotein variants.